3-Phase-Asynchrounus machine

Hello.

Im trying to an 3-phase-AM with a load on its shaft. If I just using the nominal Torwue as load, I get the right results as vlocity. But when I the add an additional weight on it, I get some weird results. The velocity become negative. I put my model in an atachment, so you can see what I´ve made.

I want the Motor to rotate the aditional load and masure the velocity and torwue.

Can anyone tell me where exactly I made an mistake pls.

Thx